Ubuntu Manpage: Streamlines - Utility for plotting a streamline representation of field flow data given two arrays

NAME

       Streamlines - Utility for plotting a streamline representation of field flow data given two arrays
       containing the vector field components on a uniform grid.

SYNOPSIS

The following two calls are the minimum required to create a streamline field flow plot using the current
interface:

• STINIT - Performs initialization tasks required before STREAM may be called to create a streamline
field flow plot. Information about the input data arrays is copied into internal common block
variables and the coordinate system mappings and boundaries are established.

• STREAM - Plots a streamline representation of field flow data, based on conditions established by
STINIT and the current values of a set of user-modifiable internal parameters associated with the
Streamlines utility.

All user-modifiable internal parameters have default values; only those which are to have values
different from the default need to be set. The routines used to set Streamlines parameters are as
follows:

• STRSET - Resets all parameters to their initial default values.

• STSETI - Sets the value of an internal parameter of type INTEGER.

• STSETR - Sets the value of an internal parameter of type REAL.

In general, once a parameter is given a value by a call to one of these routines, it retains that value
until a similar call resets it. Retrieve the value of an internal parameter by calling one of the
following routines:

• STGETI - Gets the current value of an internal parameter of type INTEGER.

• STGETR - Gets the current value of an internal parameter of type REAL.

Streamlines supports two obsolete routines for compatibility with old NCAR Graphics codes. The
compatibility mode parameter, CPM, offers a number of options that allow considerable flexibility in
making the transition to the new version of the utility. When writing new code you are encouraged not to
use these entry points, since they provide less capability than the standard Streamlines interface, and
may eventually be phased out.

• STRMLN - The principal entry point prior to Version 3.2, now a front end to the STINIT/STREAM
interface.

• EZSTRM - Front end to STRMLN: a simpler interface for standard situations, when detailed control
of the plot is not required.

C-BINDING SYNOPSIS

       c_stinit
       c_stream
       c_strset
       c_stseti
       c_stsetr
       c_stgeti
       c_stgetr
       c_strmln
       c_ezstrm

USER-MODIFIABLE INTERNAL ROUTINES

       The following routines are not to be called directly. However, you may modify them in order to customize
       the behavior of Streamlines. Three routines (STUMXY, STUIXY, and STUMTA) are provided to support user-
       defined mapping transformations. The fourth (STUMSL) allows you to tailor streamline masking to your
       requirements.

       •      STUIXY - User modifiable routine that inversely maps a single point on the streamline from user to
              data coordinate space.

       •      STUMSL - Default name for a user-definable external subroutine used to draw masked streamlines.
              The default version of the routine draws any polyline all of whose area identifiers are greater
              than or equal to zero.

       •      STUMTA - Given the coordinates of a point on the streamline in data, user, and NDC space, and the
              interpolated, normalized components of the vector at the point relative to data coordinate space,
              the user-modifiable routine STUMTA finds the directional angle of the streamline relative to NDC
              space at the point.

       •      STUMXY - User modifiable routine that maps a single point on the streamline from data to user
              coordinate space.

ACCESS

       To use Streamlines, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that
       order.

MESSAGES

In this section are listed, in alphabetical order, all the error messages that may be written by
Streamlines. Each error message begins with the name of the Streamlines routine in which an error has
been detected, followed by a dash, followed by the error message itself. These error messages are written
by a call to the error-handling support routine SETER, with a final argument indicating that the error is
fatal and that execution should be terminated.

STGETI OR STGETR - PARAMETER NAME NOT KNOWN - x
The given parameter name (´x´) is not a legal parameter name known to Streamlines.

STGETI OR STGETR - PARAMETER NAME TOO SHORT - x
The parameter name ("x") is less than three characters long.

STINIT - U AND/OR V ARRAY DIMENSIONS EXCEEDED
The STINIT input argument, M, specifying the number of array elements to use along the first
dimension of the U and V arrays, exceeds the actual first dimension of U and/or V, as specified by
the input arguments LU and LV.

STREAM - TOO MANY AREA GROUPS
The area map passed as the argument, IAM, to STREAM contains more area groups than allowed by the
Streamlines utility, currently 64. This error can occur only if the mask to area map parameter,
MSK, has a value greater than 0, specifying that streamlines are to be drawn masked to an area
map.

STREAM - INVALID AREA MAP
The area map passed as the argument, IAM, to STREAM is judged to be invalid because it contains a
negative value for the number of area groups. This error can occur only if the mask to area map
parameter, MSK, has a value greater than 0, specifying that streamlines are to be drawn masked to
an area map.

STSETI OR STSETR - PARAMETER NAME NOT KNOWN - x
The given parameter name (´x´) is not a legal parameter name known to Streamlines.

STSETI OR STSETR - PARAMETER NAME TOO SHORT - x
The parameter name ("x") is less than three characters long.

STSETI OR STSETR - PARAMETER VALUE OUT OF RANGE - x
An attempt has been made to set the parameter named ´x´ to a value outside the range allowed by
the Streamlines utility.

COPYRIGHT

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research
       The use of this Software is governed by a License Agreement.